Bistable device



y 6, 1967 T. D. READER 3,319,656

BISTABLE DEVICE Filed No v. a, 1963 Fig. 2

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9 ATTORNEYS United States Patent Ofifice 3,319,656 Patented May 16, 19673,319,656 BISTAELE DEVICE Trevor D. Reader, King of Prussia, Pa.,assignor to Sperry Rand Corporation, New York, N.Y., a cor oration ofDelaware Filed Nov. 8, 1963, 521'. No. 322,409 7 Claims. (Cl. 137625.44)

The present invention relates to fluid operated switches and moreparticularly to bistable fluid switches employing a movable blade as thebistable element. The invention provides a simple and inexpensive switchfor selectively controlling the fluid pressure at a plurality of outletsby selectively positioning a movable blade in either one of two stablestates.

An object of the present invention is to provide a bistable fluid switchfor selectively varying the pressures at a plurality of outlets.

An object of the present invention is to provide a bistable fluid switchemploying a movable blade for selectively switching one or more inputstreams toward one or more outlets.

Another object of the invention is to provide a bistable fluid switchfor selectively directing a fluid stream, said switch employing amovable blade which is held in either one of its two stable states bythe action of the fluid stream in flowing over its surface.

Still another object of the present invention is to provide a fluidswitch having a central chamber, first and second inlet means forinjecting fluid streams into the chamber in opposite directions, first,second, third, and fourth outlet means, and a movable blade forselectively directing one of said fluid streams toward said first outletand the other of said fluid streams toward said third outlet oralternatively directing one of said fluid streams toward said secondoutlet and the other of said fluid streams toward said fourth outlet.

A further feature of the invention present in one embodiment is theprovision of a binary counter comprising a rotatable blade having atorsion spring attached thereto, said blade being disposed in the pathof an intermittently generated fluid stream. The arrangement is suchthat the blade oscillates between two positions as the fluid stream isintermittently directed against the blade surface.

Cther objects of the invention and its mode of operation will becomeapparent upon consideration of the following description taken inconjunction with the accompanying drawing in which:

FIGURE 1 is a front view, partly in section, showing one stable positionof the switch;

FIGURE 2 is a front sectional view showing a second stable position ofthe switch;

FIGURE 3 is a sectional view taken along the line 33 of FIGURE 1;

FIGURE 4 is a sectional view taken along the line 44 of FIGURE 1;

FIGURES 5, 6, and 7 show wafer configurations for an exemplaryembodiment of the invention;

FIGURE 8 is a diagram for illustrating the principle of operation of theinvention;

FIGURE 9 shows a suitable control means for use in one embodiment of theinvention; and

FIGURE 10 is a schematic diagram illustrating the mode of operation of asecond embodiment of the invention.

Referring now to the drawing, a preferred embodiment of the inventioncomprises a plurality of flat plates or wafers 10, 12, 14, and 16 ofvarious configurations and a movable element or blade 18 mounted forrotational movement on a shaft 20.

The configuration of wafer 16 is shown in FIGURE 5. The wafer comprisestwo strips of wafer material separated by an open channel 22 the depthof the wafer and extending the entire length of the wafer. A hole24.extends through the wafer for the purpose of supporting the shaft 20.

The configuration of wafer 14 is shown in FIGURE 6. There are two wafers14 and each wafer has .a centrally located rectangular hole 26.

The configuration of wafer 12 is shown in FIGURE 7. There are two wafers12 and each comprises two strips of wafer material separated by an openchannel 28 the depth of the wafer and extending the entire length of thewafer. There are two wafers 10 which are substantially solid and serveas the top and bottom covers for the switch.

The wafers are stacked one on top of the other as shown in FIGURES 1-4and are fastened together by screws or other conventional fasteningmeans so that fluid cannot escape from the switch between the surfacesof adjacent wafers.

When the wafers are stacked as described above they form a substantiallysolid body having first and second inlets or input channels 30 and 32and four outlets or output channels 34, 36, 38, and 40. All input andoutput channels connect at one end with a central chamber 42. Each ofthe input and output channels is threaded at the other end to receive apipe or other fluid conducting means.

Output channels 34, 36, and 38 and 40 are connected to pipes 44, 46, 48,and 50, respectively. These pipes may be connected to one or more outputdevices (not shown). Input channels 30 and 32 are connected to pipes 52and 54, respectively, and these pipes are connected to fluid sources 56and 58 respectively. Sources 56 and 58 may be pumps or compressors andpreferably include conventional pressure regulating means to insure thatfluid is supplied to input channels 30 and 32 at a substantiallyconstant pressure.

Shaft 20 is carried in holes 24 (FIGURE 5) and extends through chamber42. The shaft intersects and is positioned perpendicular to the axis offluid streams entering the chamber from channels 30 and 32.

Blade 18 is symmetrically mounted on shaft 20 and rotates with theshaft. The blade is an elongated body having curved and symmetricallyshaped u per and lower surfaces 60 and 62. The blade is made slightlyless than the width of chamber 42 so that it does not bind against theside walls of the chamber.

The shaft 20 extends through one wall of the switch (FIGURE 3) to acontrol means 64. The control means may be any suitable device forrotating the shaft 26 in either direction to thereby move blade 18between the position shown in FIGURE 1 and the position shown in FIGURE2. It may, for example, take the form of a vane 21 connected at one endto shaft 20 and positioned between two opposing fluid jets 23 and 25 asshown in FIGURE 9. In this case the vane is alternately rotated to afirst or a second position as force is exerted against it alternately byfirst one and then the other of the jets issued by nozzles 23 and 25.Alternatively, the control means may take the form of a manuallyrotatable control knob. Preferably, the control means also includesstops or rotation-limiting means 27 and 29 for limiting the movement ofvane 21 so that blade 18 cannot be rotated in a counterclockwisedirection any further than the position shown in FIGURE 1 and cannot berotated in a clockwise direction any further than the position shown inFIGURE 2.

Assuming that fluid sources 56 and 58 are supplying fluid to inputchannels 30 and 32 and assuming further that a jet stream from nozzle 25has acted against vane 21 and thus moved blade 18 to the position shownin FIG- URE 1, the switch operates as follows.

The high velocity fluid stream entering chamber 42 from channel 32strikes blade 18 and is deflected downwardly so that it flows around theblade and into channel 38. This causes an increase in pressure inchannel 38 whichmay be transmitted by way of pipe 48 to an outputdevice.

The high velocity fluid stream flowing from channel 32 to channel 38tends to entrain molecules of'fluid from the region where channel 40connects with chamber 42. As molecules of fluid are removed from thisregion the pressure in channel 40 is decreased and this signal may betransmitted over pipe 50 to an output device. a

The high velocity fluid stream entering chamber 42 from channel 30strikes blade 18 and is deflected upwardly so that it flows around theblade and into channel 36. This causes an increase in pressure inchannel 36 which may be transmitted by way of pipe'46 to an outputdevice.

The high velocity fluid stream flowing from channel 30 toward channel 36entrains molecules of fluid from the region where channel 34 connectswith chamber 42. This causes a reduction in pressure in channel 34 andthis signal maybe transmitted over pipe 44 to an external device.

In summary, when blade 18 is in the position shown in FIGURE 1 pressureconditions are such as to tend to draw fluid into the switch throughchannels 34 and 40 and expel fluid from-the switch through channels 36and 38.

On the'other hand, when blade 18 is in the position shown in FIGURE 2pressure conditions are such as to tend to draw fluid 'into the switchthrough channels 36 and 38 and expel fluid from the switch throughchannels 34 and 40. In this case the fluid stream entering the chamberthrough channel 30 flows out through channel 40 and in'doing sowithdraws molecules of fluid from the region where channel 38 connectswith the chamber. At the same time, the fluid stream entering thechamber through channel 32 flows out through channel 34 and in doing sowithdraws molecules of fluid from the region where channel 36 connectswith the chamber.

The blade 18 is bistable. That is, once moved to one of the positionsshown in FIGURES 1 and 2 as a result of a jet stream isuing from one ofthe nozzles 23 or 25 the blade remains in this position even thoughnozzle 23 or 25 may no longer exert a force on vane 21. FIG- URE 8 is adiagram illustrating the principles which make the blade stable after itis moved to the position shown in FIGURE 1 by a jet stream issuing fromnozzle 25 against vane 21.

Vector 65 represents in a general manner the path of flow of the highvelocity fluid stream flowing fromchannel 32 toward channel 38. Themomentum of the fluid carries it in a straight line path until itstrikes the surface 62 of the blade. Because of the curvature of theblade surface and its angularposition with respect to the center line ofthe fluid stream the force is not evenly exerted over the surface areastruck by the stream. There is a stagnation point P representing thepoint of highest pressure exerted normal to the .surface 62. Thepressure exerted against surface 62 in the region of point P is greaterthanthe pressure exerted at any other point on the surface as long asfluid issues from channel 32. This force tends to rotate the blade in acounterclockwise direction thus moving vane 21 (FIGURE 9) against stop29.

Upon striking surface 62 the fluid stream issuing from channel 32 isdeflected away from the surface and tends to assume a straight line pathindicated generally at 65,. However, the fluid stream travelling path 65moves at high velocity and in doing so tends to draw molecules of fluidinto the stream from the regions surrounding the path. This reduces thepressure in the region between the fluid stream and that portion ofsurface 62 lying between points A and B. This makes the pressure onsurface 62 between points A and B less than the pressure on surface 60between points A and C. The resulting difference in forces tends torotate the blade counterclockwise so that vane 21 pushes against stop29.

A similar presure distribution exists along surface 60 as a result ofthe fluid stream issuing from channel 30. That is, the region of lowpressure exists along surface 60 between points C and D. These pressuresalso tend to rotate the blade in a counterclockwise direction.

When a jet stream from nozzle 25 strikes vane 21 and thus rotates blade18 to the position shown in FIG- UR-E 2, the fluid streams entering thechamber from channels 30 and 32 create low presure regions adjacentsurfaces 62 and 60, respectively, thus tending to rotate the blade in aclockwise direction. The reason for this is believed obvious from thediscussion of FIGURE 8. The stop mechanism prevents clockwise rotationfrom the position shown in FIGURE 2 so that the fluid forces actingagainst the blade hold it against the stop 27.

Although the invention has been described as having stops for limitingthe movement of blade 18, such stops are not absolutely necessary.Assume that no stops are provided and the control means has rotated theblade to the position shown in FIGURE 8. The different pressures actingon blade surfaces 60 and 62 tend to rotate the blade counterclockwise.However, as the blade rotates counterclockwise surface 62 near point Ais moved into the path of the fluid stream flowing'toward channel.

38 and surface'60 near point D is moved into the path of the fluidstream flowing toward channel 36. Particles of fluid in the streamsimpinge on surfaces 60 and 62 thus exerting a force on the blade whichtends to rotate it in a clockwise direction. Theoretically, there is aposition at which the force of the impinging fluid particles exactlybalances the rotational forces created by the low pressure regions. Inactual practice however, there may be a slight oscillation about thisposition if there is any variation in either of the fluid streams. Inoscillating, the points A and D may dip into the fluid stream thuscausing variations in the signals developed in the output channels. Forthis reason it is preferable to employ positive stops which prevent thepoints A and D from rotating into the paths of the fluid streams.

The present invention may be modified to function as a binary counterwherein the blade 18 alternately switches between two states in responseto fluid streams periodically directed against the blade from eitherchannel 30 or 32 or both channels simultaneously. This modification isdiagrammatically illustrated in FIGURE 10 where means such as a simpletorsion spring 70 is attached to shaft 20 and replaces the control means64 'of the embodiment previously described.

The spring 70 is adjusted such that blade '18 asumes as a normal restposition the position shown in solid outline in FIGURE 10. When a signalin the form of a fluid stream issues from channels 30 and 32 the bladerotates counterclockwise through a small angle and assumes the positionindicated in phantom outline by reference numeral 18 The forces whichcause the blade to assume position 18 are the same as those forces whichhold blade 18 of the prior embodiment in a stable position as describedwith reference to FIGURE 8.

While blade 18 is in position 18 the input stream from channel 30 flowsinto output channel 36 and the input stream from channel 32 flows intooutput channel 38. Thus, output signals manifested by high pressure areproduced in channels 36 and 38 while output signals manifested by lowpressure are produced in channels 34 and 40.

The blade maintains the position 18 only as long as fluid streams issuefrom channels 30 and 32. Energy was stored in the torsion spring whenthe blade 18 was rotated from its rest position to position 18 Upontermination of the fluid streams this energy is expended in rotating theblade, from position 18 toward the rest position. However, the springcauses the blade to overshoot the rest position and swing towardposition 18 If channels 30 and 32 issue fluid streams at this time theforces acting against blade 18 cause it to assume position 18 While theblade is in position 18 the input stream from channel 30 flows intooutput channel 40 and the input stream from channel 32 flows into outputchannel 34.

The blade maintains position 18 only as long as input streams issue fromchannels 30 and 32. Upon termination of the input streams the bladebegins to rotate in a counterclockwise direction in response to theforce exerted by the spring. Again, the blade overshoots the restposition so that it moves once more toward position 18 If channels 30and 32 again issue fluid streams the blade is driven to position 18 sothat high pressure signals are manifested in output channels 36 and 38and low pressure signal-s are manifested in output channels 34 and 40.This completes one cycle of operation of the device.

In summary, each fluid stream pulse issued by channels 30 and 32 causesthe blade to alternately assume a first or a second state. Considering aparticular output, an output signal is produced for every two inputsignals applied to the device. This mode of operation corresponds tothat of a binary or modulo-2 counter.

There is a restriction on the interval of time which must elapse betweeninput signals applied to channels 30 and 32. A period of timeapproximately equal to a half cycle of the natural frequency of theblade and its shaft must elapse between the termination of one inputsignal and the initiation of the next.

While preferred embodiments of the invention have been shown anddescribed herein, various substitutions, additions and omissions arereadily apparent. For example, in an embodiment having a separate inputcontrol means 64 one of the input channels, say channel 32, may beomitted and fluid injected into the chamber only from channel 30. Also,if only input channel 30 is provided then either one or both of outputchannels 34 and 38 may be eliminated. In some instances it may bedesirable to connect a pointer or visual indicator to shaft 20 toprovide a visual indication of the state of the switch. Constructionsother than the wafer construction may be employed without departing fromthe spirit and scope of the invention as defined in the subjoinedclaims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A fluid switch comprising: first means for producing a first highvelocity fluid stream, a movable element mounted for rotating movementin the path of said fluid stream about an axis extending substantiallyperpendicular to the axis of said stream, said movable element havingfirst and second surfaces shaped such that said fluid stream tends torotate said movable element to a first position when it strikes saidfirst surface and rotates said movable element to a second position whenit strikes said second surface, a torsion spring connected to saidmovable element for normally biasing said movable element at an angularposition intermediate said first and second posi tions, means includedwithin said first means for intermitrtently terminating said firststream for a period of time equal to approximately one-half cycle of anatural frequency of said spring and movable element, means forselectively rotating said movable element so that said fluid streamselectively strikes said first and second surfaces.

2. A fluid switch as claimed in claim 1 and further comprising a secondmeans for producing a second high velocity fluid stream substantiallycoaxial with but opposing said first stream, said movable element beingdisposed between said streams, said second means including means forintermittently terminating said second stream for a period of time equalto approximately one-half cycle of the natural frequency of said springand movable element.

3. A fluid switch as claimed in claim 2 and further comprising firstreceiving means for receiving said first stream after it strikes asurface of said movable element and second receiving means for receivingsaid second stream after it strikes a surface of said movable element.

4. A fluid switch as claimed in claim 3 and further comprising meansdefining a chamber, said movable element being disposed in said chamber,said first and second receiving means comprising fluid channelsterminating at openings in said chamber.

5. A fluid switch comprising: a body having a chamber formed therein; amovable element mounted in said chamher for rotational movement betweenfirst and second positions and having first and second curved surfaces;torsion spring :means for normally holding said movable element in aposition intermediate said first and second positions; meansintermittently injecting a fluid stream into said chamber against saidmovable element whereby said stream may strike said first or said secondsurface depending upon the rotational position of said movable element;said stream acting against said first surface to rotate said element tosaid first position and store energy in said spring means or actingagainst said second surface to rotate said element to said secondposition and store energy in said spring means, the energy so storedbeing sufficient to rotate said movable element from one of said firstand second positions to the other during the periods between successiveinjections of said fluid stream; and outlet means connected to saidchamber for producing from said fluid stream fluid signals indicatingwhether said movable element is in said first or said second position.

6. A fluid switch comprising: means defining a fluid chamber; means forinjecting into said chamber in opposing directions first and second highvelocity fluid streams; a movable element mounted in said chamber forrotating movement in the paths of said fluid streams about an axisextending through the axes of said streams; means for selectivelyrotating said movable element to a first or a second position; and aplurality of output channels connected to said chamber for selectivelyreceiving said fluid streams after they are diverted by said movableelement, said movable element having two curved surfaces for divertingsaid fluid streams, said surfaces being shaped such that said fluidstreams exert forces thereon tending to hold said movable element insaid first or said second position after it has been rotated thereto.

"7. A fluid switch comprising: means defining a fluid chamber, means forinjecting fluid into said chamber, at least first and second channelmeans terminating first and second openings in said chamber, a movableelement pivotally mounted about an axis substantially perpendicular toand in the path of said injected fluid for selectively directing saidinjected fluid across said first opening and into said second opening tothereby increase the pressure at said second opening and decrease thepressure at said first opening, said movable element having a surfaceaerodynamically shaped so that said injected fluid tends to hold saidelement in a predetermined position as it flows over said surface, meansfor selectively pivoting said movable element about said axis to saidpredetermined position, third channel means terminating at a thirdopening in said chamber, means for selectively pivoting said movableelement about said axis to a second predetermined position whereby saidinjected fluid flows over a second surface of said element and towardssaid third opening, said second surface being aerodynamically shaped sothat said injected fluid tends to hold said element in said secondpredetermined position as it flows over said second surface.

References Cited by the Examiner UNITED STATES PATENTS 787,565 4/ 1905Coryell 137-625 1,905,733 4/1933 Moore l3781 2,777,251 1/1957 Bailey46-179 3,102,389 9/1963 Pedersen l3781 3,223,103 12/1965 Trinkler 137-81M. CARY NELSON, Primary Examiner. W. R. CLINE, Assistant Examiner.

6. A FLUID SWITCH COMPRISING: MEANS DEFINING A FLUID CHAMBER; MEANS FORINJECTING INTO SAID CHAMBER IN OPPOSING DIRECTIONS FIRST AND SECOND HIGHVELOCITY FLUID STREAMS; A MOVABLE ELEMENT MOUNTED IN SAID CHAMBER FORROTATING MOVEMENT IN THE PATHS OF SAID FLUID STREAMS ABOUT AN AXISEXTENDING THROUGH THE AXES OF SAID STREAMS; MEANS FOR SELECTIVELYROTATING SAID MOVABLE ELEMENT TO A FIRST OR A SECOND POSITION; AND APLURALITY OF OUTPUT CHANNELS CONNECTED TO SAID CHAMBER FOR SELECTIVELYRECEIVING SAID FLUID STREAMS AFTER THEY ARE DIVERTED BY SAID MOVABLEELEMENT, SAID MOVABLE ELEMENT HAVING TWO CURVED SURFACES FOR DIVERTINGSAID FLUID STREAMS, SAID SURFACES BEING SHAPED SUCH THAT SAID FLUIDSTREAMS EXERT FORCES THEREON TENDING TO HOLD SAID MOVABLE ELEMENT INSAID FIRST OR SAID SECOND POSITION AFTER IT HAS BEEN ROTATED THERETO.